The present invention is related generally to personal watercraft. More specifically, the present invention is related to personal watercraft having adjustable sponsons.
Personal watercraft have become increasingly popular in recent years. A personal watercraft, also known as a xe2x80x9cjet skixe2x80x9d typically has a bottom hull, handle bars for steering, a tunnel within the bottom hull, a jet pump located within the bottom tunnel, and an engine within the hull under the top deck for driving the jet pump. The jet pump typically pulls in water from the front of the tunnel under the boat, and discharges the water at high velocity through a steerable nozzle at the rear of the boat. The handle bars are typically coupled to the nozzle, which is the steering mechanism for the personal watercraft. The watercraft commonly has a straddle-type seat and foot wells disposed on either side of the seat.
Early watercraft often had longitudinal chines running underneath the bottom hull, and sometimes had steps located in the rear portion of the bottom hull, for reducing porpoising by extending the length of the boat while not extending the length of wetted surface. Steering, as previously indicated, was primarily effected by turning the handle bars coupled to the nozzle, which could be steered from side to side to direct the water jet in the desired direction and thereby steer the personal watercraft. The steerable nozzle sometimes had a small rudder on the nozzle, also for aiding in steering the watercraft.
Early personal watercraft sometimes skidded around corners wider than the driver desired. Sometimes, boats would turn 180xc2x0, despite the driver""s intent to make a sharp 90xc2x0 turn. This lack of control at high speeds during aggressive maneuvers was later addressed by adding sponsons to the personal watercraft.
The term xe2x80x9csponsonxe2x80x9d has come to have different meanings in different contexts. Historically, sponsons were floatation devices or outriggers for stabilizing a boat in rough water. The sponsons could be lowered to stabilize a boat in rough water, for example, while fishing. The sponsons could be later raised for traveling through the water. The term sponson has also been used to refer to the outrigger on an outrigger canoe. As used in the personal watercraft industry, and as used in the present application, the term sponson refers to a device having a generally hydrodynamic shape to aid the watercraft in stabilizing straight ahead progress through the water and to aid in executing turns in the water. The personal watercraft sponsons are dimensioned and configured to have a fin or blade having an outwardly extending edge that penetrates below the water level during normal use. The personal watercraft""s sponson will penetrate below the water surface when the personal watercraft is at rest, in calm water, even with no rider on board. The sponson typically has an outwardly extending lower surface that rides on the water when the boat is planing.
Sponsons provide lift at the rear of the personal watercraft, acting to force the nose down to provide a degree of aggressiveness. Sponsons that provide harder, sharper cornering often also provide decreased straight line stability. The more aggressive design often has a xe2x80x9ctippyxe2x80x9d feeling when the rider shifts their weight. This tippy feeling is accepted by experienced drivers, but maybe unsettling to experienced drivers. Sponsons are typically designed together with the personal watercraft hull, for a particular model and year. Various considerations go into the hull and sponson design, including the desired degree of stability, desired lift provided by the sponson, and the degree of aggressiveness desired for that model and model year. Different drivers desiring different features can select varying personal watercraft having the desired handling characteristics.
What would be desirable are personal watercraft having sponsons which can vary according to the desired handling characteristics of the driver. What would be advantageous are sponsons which can be changed from an aggressive handling mode to a gentler riding mode.
The present invention provides tunable sponsons for personal watercraft and watercraft having these tunable sponsons. Sponsons according to the present invention can be adjusted or xe2x80x9ctuned,xe2x80x9d by adjusting the effective height of the lower surface of a horizontally extending portion of the sponson relative to the water. One tunable sponson includes a horizontally or outwardly extending portion, followed by a downwardly extending fin portion, terminating in a fin edge for penetrating beneath the water surface. The lower surface of the sponson can include apertures for mounting an additional material thickness under the sponson.
One tunable sponson includes a horizontal underside having threaded apertures for receiving mounting bolts for securing an additional thickness or slab of material under the existing lower horizontal surface of the sponson. The effective height of the sponson lower horizontal surface relative to the water can be decreased or lowered by increasing the thickness of the sponson material. The additional thickness or slab of material may also be referred to as a sponson extension. The effective height of a tunable sponson lower horizontal surface may be increased or raised by removing a previously installed thickness of sponson extension material.
The present invention provides sponsons which can have the sponson height relative to the water increased or decreased to match the driver""s experience level, the driver""s desires of the moment, the passenger load, as well as the expected water conditions. The tunable sponsons thus allow the driver to configure their own handling characteristics moment by moment, rather than having these characteristics dictated by the manufacturer.